Organizations typically have tens, hundreds, or thousands of computer users. Historically, each computer user has had his or her own client computing device. The client computing devices of all the computer users are usually connected to one another via a network, which eases administration of the devices to great extent. However, some maintenance is still typically needed on the client computing devices themselves, which means that administrators and other information technology (IT) personnel periodically have to visit each client computing device, which is time-consuming and costly. Furthermore, providing a separate computing device to each computer user is itself a costly endeavor.
Therefore, more recently, many organizations have migrated their computing resources to a terminal services-type environment, which is also referred to herein as a virtual client computing environment. In these types of environments, a central server computing device hosts a large number of computer users, with each user assigned to a separate session running within the operating system on the server computing device. Each computer user still has a client computing device, but such client computing devices act primarily as dumb terminals. Users provide input at the client computing devices, and the client computing devices provide output to the users, but otherwise all application program processing is performed at the server computing device. Examples of such virtual client computing environments include the Microsoft Windows® Terminal Services environment, and virtual client computing environments available from Citrix Systems of Fort Lauderdale, Fla.
Virtual client computing environments are advantageous for at least two reasons. First, the client computing devices of the computing users, because they only perform input/output functionality, do not have to be very sophisticated. As a result, the cost-per-user is decreased substantially. Instead of having the latest, and expensive, processor and other hardware components, for instance, a client computing device can have a cheaper, and slower, processor, as well as other cheaper hardware components. Overall performance is not degraded, because primary application program processing is performed at the server computing device, not at the client computing device.
Second, maintenance on such multiple-user systems is substantially performed at the server computing device itself, and not at the client computing devices. For instance, upgrading memory, processing power, hard disk drive storage, and so on, is provided by increasing these resources at the server computing device, not at the client computing devices. As a result, maintenance costs incurred by IT personnel are reduced, because the IT personnel do not have to visit each client computing device to perform many regular maintenance tasks.
One downside to employing a virtual client computing environment is in the area of graphics processing. Sophisticated graphics processing is typically performed at least in part by dedicated graphics hardware, and not solely in software. Graphics-related commands are standardized in accordance with standards such as OpenGL. An application program running on a computing device provides such graphics-related commands to the operating system running on the computing device. The operating system in turn conveys these commands to the graphics hardware of the computing device, which processes them for rendering on the display device of the computing device, or for reporting back to the application program. Having dedicated graphics hardware process the graphics-related commands provides for graphics processing that is usually many orders of magnitude faster than if such graphics-related commands were processed in software—that is, by a processor of the computing device, like any other software, and not aided by specialized hardware.
Virtual client computing environments are not well situated to take advantage of dedicated graphics hardware to process graphics-related commands, however. If the graphics hardware is located at the client computing device itself, it cannot be employed by the client application programs running within a virtual client computing environment on a server computing device. This is because the client application programs run within the confines of the operating system provided on the server computing device, and thus do not have access to the graphics hardware on the client computing devices themselves for processing graphics-related commands. Furthermore, even if such access were possible, adding expensive graphics hardware to client computing devices defeats the purpose of having virtual client computing environments in the first place, which is to save costs by having the client computing devices acting primarily as dumb terminals.
In addition, if the graphics hardware is located at the server computing device, it typically cannot be employed by client application programs running within virtual client computing environments on the server computing device. For example, in a Microsoft Windows® environment, the graphics hardware may be accessed directly only by server application programs running on the server computing device, and not by client application programs running within virtual client computing environments on the server computing device.
A solution to this problem in Linux® environments is found in the Deep Computing Visualization (DCV) product available from International Business Machines, Inc., of Armonk, N.Y. DCV generally allows the graphics hardware of a server computing device to be leveraged by client application programs running within virtual client computing environments on the server computing device, even where the output of such programs is displayed at the client computing devices, and not at the server computing device. DCV utilizes various inter-process communication (IPC) mechanisms so that client application programs can pass graphics-related commands to the graphics hardware of the server computing device, the responses to which are then passed back to the programs themselves or displayed at the client computing devices.
However, it has been found that DCV provides for less than optimal performance in graphics-related command processing in Microsoft Windows® environments. Insofar as the point of accessing the graphics hardware of the server computing device for the benefit of the client computing devices is to enhance graphics performance, the less than optimal performance of DCV means that it is not an adequate solution to this problem. Therefore, there is a need for allowing client application programs running within virtual client computing environments on Microsoft Windows®-based server computing devices to leverage the graphics hardware of such server computing devices for the benefit of client computing devices. Such leveraging should provide performance approaching that as if the graphics hardware were installed on the client computing devices themselves and accessible by the client application programs. For these and other reasons, therefore; there is a need for the present invention.